Vertical shaft impact crushers (VSI-crushers) are used in many applications for crushing hard material, such as rocks, ore, etc.
WO 2008/147274 describes one example of such a VSI-crusher. A VSI-crusher includes a housing and a horizontal rotor located inside the housing. Material that is to be crushed is fed into the rotor via an opening in the top thereof. With the aid of centrifugal force, the rotating rotor ejects the material against the wall of the housing. On impact with the wall of the housing, the material is crushed to a desired size. The housing wall could be provided with anvils or have a bed of retained material against which the accelerated material is crushed.
The rotor of a VSI-crusher usually has a horizontal upper disc and a horizontal lower disc. The upper and lower discs are connected with a vertical rotor wall. The upper disc has an aperture for feeding material into the rotor. The material lands on the lower disc and is then thrown out of the rotor via openings in the rotor wall. A replaceable center distributor plate is mounted on the horizontal lower disc to protect the same from the material fed to the rotor. The center distributor plate is in some crushing processes subjected to heavy wear, resulting in a need for frequently replacing a worn and/or damaged distributor plate, a task that is complicated and time consuming.